In recent years the role of the human behavioral response to Human Immunodeficiency Virus (HIV) serostatus notification as well as to coping with HIV infection and its sequellae have garnered increased interest as components of the pathogenic mechanisms of HIV disease. Both field and laboratory studies have demonstrated that both acute and chronic psychological stress can modify the immune system. Laboratory speech stressors stimulate a rapid (within 3 minutes) lymphocytosis and alter functional activity of the lymphocytes as evidenced by decreased proliferation in response to mitogenic stimuli. In individuals infected with HIV, the response to the speech stressor is altered with increased lymphocytosis and inhibited lymphoproliferative response to a mitogenic stimulus. Chronic stress, such as living with HIV, is also associated with decreased lymphocyte function. This project proposes to use flow cytometric methods to assess the cytokine production potential of lymphocytes on a cell by cell basis with the following aims: 1) To determine whether baseline intracellular cytokine production profiles of lymphocyte subsets (T helper, T cytotoxic, B, and NK cells) differ between HIV seronegative and HIV infected individuals; 2)To determine whether HIV+ individuals respond to a speech stressor with a change in specific cytokine profiles (i.e., Type 1 vs. Type 2 cytokine producing) as a function of changes in lymphocytes subsets. 3a) To determine the relation between baseline cytokine levels and speech stress-induced changes in lymphocyte subsets and immune function. 3b) To determine the relation between speech stress-induced cytokine responses and speech stress-induced changes in lymphocyte subsets and immune function. This project will be conducted using residual blood samples from an ongoing program project in our laboratory.